Steerable endoscope and improved method of insertion

ABSTRACT

A steerable endoscope has an elongated body with a selectively steerable distal portion and an automatically controlled proximal portion. The endoscope body is inserted into a patient and the selectively steerable distal portion is used to select a desired path within the patient&#39;s body. When the endoscope body is advanced, an electronic motion controller operates the automatically controlled proximal portion to assume the selected curve of the selectively steerable distal portion. Another desired path is selected with the selectively steerable distal portion and the endoscope body is advanced again. As the endoscope body is further advanced, the selected curves propagate proximally along the endoscope body, and when the endoscope body is withdrawn proximally, the selected curves propagate distally along the endoscope body. This creates a serpentine motion in the endoscope body that allows it to negotiate tortuous curves along a desired path through or around and between organs within the body.

CROSS-REFERENCE TO OTHER APPLICATIONS

The present application claims priority of U.S. Provisional PatentApplication No. 60/194,140, filed Apr. 3, 2000.

FIELD OF THE INVENTION

The present invention relates generally to endoscopes and endoscopicmedical procedures. More particularly, it relates to a method andapparatus to facilitate insertion of a flexible endoscope along atortuous path, such as for colonoscopic examination and treatment.

BACKGROUND OF THE INVENTION

An endoscope is a medical instrument for visualizing the interior of apatient's body. Endoscopes can be used for a variety of differentdiagnostic and interventional procedures, including colonoscopy,bronchoscopy, thoracoscopy, laparoscopy and video endoscopy.

Colonoscopy is a medical procedure in which a flexible endoscope, orcolonoscope, is inserted into a patient's colon for diagnosticexamination and/or surgical treatment of the colon. A standardcolonoscope is typically 135-185 cm in length and 12-13 mm in diameter,and includes a fiberoptic imaging bundle, illumination fibers and one ortwo instrument channels that may also be used for insufflation orirrigation. The colonoscope is inserted via the patient's anus and isadvanced through the colon, allowing direct visual examination of thecolon, the ileocecal valve and portions of the terminal ileum. Insertionof the colonoscope is complicated by the fact that the colon representsa tortuous and convoluted path. Considerable manipulation of thecolonoscope is often necessary to advance the colonoscope through thecolon, making the procedure more difficult and time consuming and addingto the potential for complications, such as intestinal perforation.Steerable colonoscopes have been devised to facilitate selection of thecorrect path though the curves of the colon. However, as the colonoscopeis inserted farther and farther into the colon, it becomes moredifficult to advance the colonoscope along the selected path. At eachturn, the wall of the colon must maintain the curve in the colonoscope.The colonoscope rubs against the mucosal surface of the colon along theoutside of each turn. Friction and slack in the colonoscope build up ateach turn, making it more and more difficult to advance and withdraw thecolonoscope. In addition, the force against the wall of the colonincreases with the buildup of friction. In cases of extreme tortuosity,it may become impossible to advance the colonoscope all of the waythrough the colon.

Steerable endoscopes, catheters and insertion devices for medicalexamination or treatment of internal body structures are described inthe following U.S. patents, the disclosures of which are herebyincorporated by reference in their entirety: U.S. Pat. No. 4,753,223;5,337,732; 5,662,587; 4,543,090; 5,383,852; 5,487,757 and 5,337,733.

SUMMARY OF THE INVENTION

In keeping with the foregoing discussion, the present invention takesthe form of a steerable endoscope for negotiating tortuous paths througha patient's body. The steerable endoscope can be used for a variety ofdifferent diagnostic and interventional procedures, includingcolonoscopy, bronchoscopy, thoracoscopy, laparoscopy and videoendoscopy. The steerable endoscope is particularly well suited fornegotiating the tortuous curves encountered when performing acolonoscopy procedure.

The steerable endoscope has an elongated body with a manually orselectively steerable distal portion and an automatically controlledproximal portion. The selectively steerable distal portion can beselectively steered or bent up to a fill 180 degree bend in anydirection. A fiberoptic imaging bundle and one or more illuminationfibers extend through the body from the proximal end to the distal end.Alternatively, the endoscope can be configured as a video endoscope witha miniaturized video camera, such as a CCD camera, which transmitsimages to a video monitor by a transmission cable or by wirelesstransmission. Optionally, the endoscope may include one or twoinstrument channels that may also be used for insufflation orirrigation.

A proximal handle attached to the elongate body includes an ocular fordirect viewing and/or for connection to a video camera, a connection toan illumination source and one or more luer lock fittings that areconnected to the instrument channels. The handle is connected to asteering control for selectively steering or bending the selectivelysteerable distal portion in the desired direction and to an electronicmotion controller for controlling the automatically controlled proximalportion of the endoscope. An axial motion transducer is provided tomeasure the axial motion of the endoscope body as it is advanced andwithdrawn. Optionally, the endscope may include a motor or linearactuator for automatically advancing and withdrawing the endoscope.

The method of the present invention involves inserting the distal end ofthe endoscope body into a patient, either through a natural orifice orthrough an incision, and steering the selectively steerable distalportion to select a desired path. When the endoscope body is advanced,the electronic motion controller operates the automatically controlledproximal portion of the body to assume the selected curve of theselectively steerable distal portion. This process is repeated byselecting another desired path with the selectively steerable distalportion and advancing the endoscope body again. As the endoscope body isfurther advanced, the selected curves propagate proximally along theendoscope body. Similarly, when the endoscope body is withdrawnproximally, the selected curves propagate distally along the endoscopebody. This creates a sort of serpentine motion in the endoscope bodythat allows it to negotiate tortuous curves along a desired path throughor around and between organs within the body.

The method can be used for performing colonoscopy or other endoscopicprocedures, such as bronchoscopy, thoracoscopy, laparoscopy and videoendoscopy. In addition, the apparatus and methods of the presentinvention can be used for inserting other types of instruments, such assurgical instruments, catheters or introducers, along a desired pathwithin the body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a prior art colonoscope being employed for a colonoscopicexamination of a patient's colon.

FIG. 2 shows a first embodiment of the steerable endoscope of thepresent invention.

FIG. 3 shows a second embodiment of the steerable endoscope of thepresent invention.

FIG. 4 shows a third embodiment of the steerable endoscope of thepresent invention.

FIG. 5 shows a fourth embodiment of the steerable endoscope of thepresent invention.

FIG. 6 shows a wire frame model of a section of the body of theendoscope in a neutral or straight position.

FIG. 7 shows the wire frame model of the endoscope body shown in FIG. 6passing through a curve in a patient's colon.

FIGS. 8-13 show the endoscope of the present invention being employedfor a colonoscopic examination of a patient's colon.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a prior art colonoscope 500 being employed for acolonoscopic examination of a patient's colon C. The colonoscope 500 hasa proximal handle 506 and an elongate body 502 with a steerable distalportion 504. The body 502 of the colonoscope 500 has been lubricated andinserted into the colon C via the patient's anus A. Utilizing thesteerable distal portion 504 for guidance, the body 502 of thecolonoscope 500 has been maneuvered through several turns in thepatient's colon C to the ascending colon G. Typically, this involves aconsiderable amount of manipulation by pushing, pulling and rotating thecolonoscope 500 from the proximal end to advance it through the turns ofthe colon C. After the steerable distal portion 504 has passed, the wallof the colon C maintains the curve in the flexible body 502 of thecolonoscope 500 as it is advanced. Friction develops along the body 502of the colonoscope 500 as it is inserted, particularly at each turn inthe colon C. Because of the friction, when the user attempts to advancethe colonoscope 500, the body 502′ tends to move outward at each curve,pushing against the wall of the colon C, which exacerbates the problemby increasing the friction and making it more difficult to advance thecolonoscope 500. On the other hand, when the colonoscope 500 iswithdrawn, the body 502″ tends to move inward at each curve taking upthe slack that developed when the colonoscope 500 was advanced. When thepatient's colon C is extremely tortuous, the distal end of the body 502becomes unresponsive to the user's manipulations, and eventually it maybecome impossible to advance the colonoscope 500 any farther. Inaddition to the difficulty that it presents to the user, tortuosity ofthe patient's colon also increases the risk of complications, such asintestinal perforation.

FIG. 2 shows a first embodiment of the steerable endoscope 100 of thepresent invention. The endoscope 100 has an elongate body 102 with amanually or selectively steerable distal portion 104 and anautomatically controlled proximal portion 106. The selectively steerabledistal portion 104 can be selectively steered or bent up to a full 180degree bend in any direction. A fiberoptic imaging bundle 112 and one ormore illumination fibers 114 extend through the body 102 from theproximal end 110 to the distal end 108. Alternatively, the endoscope 100can be configured as a video endoscope with a miniaturized video camera,such as a CCD camera, positioned at the distal end 108 of the endoscopebody 102. The images from the video camera can be transmitted to a videomonitor by a transmission cable or by wireless transmission. Optionally,the body 102 of the endoscope 100 may include one or two instrumentchannels 116, 118 that may also be used for insufflation or irrigation.The body 102 of the endoscope 100 is highly flexible so that it is ableto bend around small diameter curves without buckling or kinking. Whenconfigured for use as a colonoscope, the body 102 of the endoscope 100is typically from 135 to 185 cm in length and approximately 12-13 mm indiameter. The endoscope 100 can be made in a variety of other sizes andconfigurations for other medical and industrial applications.

A proximal handle 120 is attached to the proximal end 110 of theelongate body 102. The handle 120 includes an ocular 124 connected tothe fiberoptic imaging bundle 112 for direct viewing and/or forconnection to a video camera 126. The handle 120 is connected to anillumination source 128 by an illumination cable 134 that is connectedto or continuous with the illumination fibers 114. A first luer lockfitting 130 and a second luer lock fitting 132 on the handle 120 areconnected to the instrument channels 116, 118.

The handle 120 is connected to an electronic motion controller 140 byway of a controller cable 136. A steering control 122 is connected tothe electronic motion controller 140 by way of a second cable 138. Thesteering control 122 allows the user to selectively steer or bend theselectively steerable distal portion 104 of the body 102 in the desireddirection. The steering control 122 may be a joystick controller asshown, or other known steering control mechanism. The electronic motioncontroller 140 controls the motion of the automatically controlledproximal portion 106 of the body 102. The electronic motion controller140 may be implemented using a motion control program running on amicrocomputer or using an application-specific motion controller.Alternatively, the electronic motion controller 140 may be implementedusing a neural network controller.

An axial motion transducer 150 is provided to measure the axial motionof the endoscope body 102 as it is advanced and withdrawn. The axialmotion transducer 150 can be made in many possible configurations. Byway of example, the axial motion transducer 150 in FIG. 2 is configuredas a ring 152 that surrounds the body 102 of the endoscope 100. Theaxial motion transducer 150 is attached to a fixed point of reference,such as the surgical table or the insertion point for the endoscope 100on the patient's body. As the body 102 of the endoscope 100 slidesthrough the axial motion transducer 150, it produces a signal indicativeof the axial position of the endoscope body 102 with respect to thefixed point of reference and sends a signal to the electronic motioncontroller 140 by telemetry or by a cable (not shown). The axial motiontransducer 150 may use optical, electronic or mechanical means tomeasure the axial position of the endoscope body 102. Other possibleconfigurations for the axial motion transducer 150 are described below.

FIG. 3 shows a second embodiment of the endoscope 100 of the presentinvention. As in the embodiment of FIG. 2, the endoscope 100 has anelongate body 102 with a selectively steerable distal portion 104 and anautomatically controlled proximal portion 106. The steering control 122is integrated into proximal handle 120 in the form or one or two dialsfor selectively steering the selectively steerable distal portion 104 ofthe endoscope 100. Optionally, the electronic motion controller 140 maybe miniaturized and integrated into proximal handle 120, as well. Inthis embodiment, the axial motion transducer 150 is configured with abase 154 that is attachable to a fixed point of reference, such as thesurgical table. A first roller 156 and a second roller 158 contact theexterior of the endoscope body 102. A multi-turn potentiometer 160 orother motion transducer is connected to the first roller 156 to measurethe axial motion of the endoscope body 102 and to produce a signalindicative of the axial position.

The endoscope 100 may be manually advanced or withdrawn by the user bygrasping the body 102 distal to the axial motion transducer 150.Alternatively, the first roller 156 and/or second roller 158 may beconnected to a motor 162 for automatically advancing and withdrawing thebody 102 of the endoscope 100.

FIG. 4 shows a third embodiment of the endoscope 100 of the presentinvention, which utilizes an elongated housing 170 to organize andcontain the endoscope 100. The housing 170 has a base 172 with a lineartrack 174 to guide the body 102 of the endoscope 100. The housing 170may have an axial motion transducer 150′ that is configured as a linearmotion transducer integrated into the linear track 174. Alternatively,the housing 170 may have an axial motion transducer 150″ configuredsimilarly to the axial motion transducer 150 in FIG. 2 or 3. Theendoscope 100 may be manually advanced or withdrawn by the user bygrasping the body 102 distal to the housing 170. Alternatively, thehousing 170 may include a motor 176 or other linear motion actuator forautomatically advancing and withdrawing the body 102 of the endoscope100. In another alternative configuration, a motor with friction wheels,similar to that described above in connection with FIG. 3, may beintegrated into the axial motion transducer 150″.

FIG. 5 shows a fourth embodiment of the endoscope 100 of the presentinvention, which utilizes a rotary housing 180 to organize and containthe endoscope 100. The housing 180 has a base 182 with a rotating drum184 to guide the body 102 of the endoscope 100. The housing 180 may havean axial motion transducer 150′″ that is configured as a potentiometerconnected to the pivot axis 186 of the rotating drum 184. Alternatively,the housing 180 may have an axial motion transducer 150″ configuredsimilarly to the axial motion transducer 150 in FIG. 2 or 3. Theendoscope 100 may be manually advanced or withdrawn by the user bygrasping the body 102 distal to the housing 180. Alternatively, thehousing 180 may include a motor 188 connected to the rotating drum 184for automatically advancing and withdrawing the body 102 of theendoscope 100. In another alternative configuration, a motor withfriction wheels, similar to that described above in connection with FIG.3, maybe integrated into the axial motion transducer 150″.

FIG. 6 shows a wire frame model of a section of the body 102 of theendoscope 100 in a neutral or straight position. Most of the internalstructure of the endoscope body 102 has been eliminated in this drawingfor the sake of clarity. The endoscope body 102 is divided up intosections 1, 2, 3 . . . 10, etc. The geometry of each section is definedby four length measurements along the a, b, c and d axes. For example,the geometry of section 1 is defined by the four length measurementsl_(1a), l_(1b), l_(1c), l_(1d), and the geometry of section 2 is definedby the four length measurements l_(2a), l_(2b), l_(2c), l_(2d), etc.Preferably, each of the length measurements is individually controlledby a linear actuator (not shown). The linear actuators may utilize oneof several different operating principles. For example, each of thelinear actuators may be a self-heating NiTi alloy linear actuator or anelectrorheological plastic actuator, or other known mechanical,pneumatic, hydraulic or electromechanical actuator. The geometry of eachsection may be altered using the linear actuators to change the fourlength measurements along the a, b, c and d axes. Preferably, the lengthmeasurements are changed in complementary pairs to selectively bend theendoscope body 102 in a desired direction. For example, to bend theendoscope body 102 in the direction of the a axis, the measurementsl_(1a), l_(2a), l_(3a) . . . l_(10a) would be shortened and themeasurements l_(1b), l_(2b), l_(3b) . . . l_(10b) would be lengthened anequal amount. The amount by which these measurements are changeddetermines the radius of the resultant curve.

In the selectively steerable distal portion 104 of the endoscope body102, the linear actuators that control the a, b, c and d axismeasurements of each section are selectively controlled by the userthrough the steering control 122. Thus, by appropriate control of the a,b, c and d axis measurements, the selectively steerable distal portion104 of the endoscope body 102 can be selectively steered or bent up to afull 180 degrees in any direction.

In the automatically controlled proximal portion 106, however, the a, b,c and d axis measurements of each section are automatically controlledby the electronic motion controller 140, which uses a curve propagationmethod to control the shape of the endoscope body 102. To explain howthe curve propagation method operates, FIG. 7 shows the wire frame modelof a part of the automatically controlled proximal portion 106 of theendoscope body 102 shown in FIG. 6 passing through a curve in apatient's colon C. For simplicity, an example of a two-dimensional curveis shown and only the a and b axes will be considered. In athree-dimensional curve all four of the a, b, c and d axes would bebrought into play.

In FIG. 7, the endoscope body 102 has been maneuvered through the curvein the colon C with the benefit of the selectively steerable distalportion 104 (this part of the procedure is explained in more detailbelow) and now the automatically controlled proximal portion 106 residesin the curve. Sections 1 and 2 are in a relatively straight part of thecolon C, therefore l_(1a)=l_(1b) and l_(2a)=l_(2b). However, becausesections 3-7 are in the S-shaped curved section, l_(3a)<l_(3b),l_(4a)<l_(4b) and l_(5a)<l_(5b), but l_(6a)>l_(6b), l_(7a)>l_(7b) andl_(8a)>l_(8b). When the endoscope body 102 is advanced distally by oneunit, section 1 moves into the position marked 1′, section 2 moves intothe position previously occupied by section 1, section 3 moves into theposition previously occupied by section 2, etc. The axial motiontransducer 150 produces a signal indicative of the axial position of theendoscope body 102 with respect to a fixed point of reference and sendsthe signal to the electronic motion controller 140. Under control of theelectronic motion controller 140, each time the endoscope body 102advances one unit, each section in the automatically controlled proximalportion 106 is signaled to assume the shape of the section thatpreviously occupied the space that it is now in. Therefore, when theendoscope body 102 is advanced to the position marked 1′, l_(1a)=l_(1b),l_(2a)=l_(2b), l_(3a)=l_(3b), l_(4a)<l_(4b), l_(5a)<l_(5b),l_(6a)<l_(6b), l_(7a)>l_(7b), l_(8a)>l_(8b), and l_(9a)>l_(9b), and,when the endoscope body 102 is advanced to the position marked 1″,l_(1a)=l_(1b), l_(2a)=l_(2b), l_(3a)=l_(3b), l_(4a)=l_(4b),l_(5a)<l_(5b), l_(6a)<l_(6b), l_(7a)<l_(7b), l_(8a)>l_(8b),l_(9a)>l_(9b), and l_(10a)>l_(10b). Thus, the S-shaped curve propagatesproximally along the length of the automatically controlled proximalportion 106 of the endoscope body 102. The S-shaped curve appears to befixed in space, as the endoscope body 102 advances distally.

Similarly, when the endoscope body 102 is withdrawn proximally, eachtime the endoscope body 102 is moved proximally by one unit, eachsection in the automatically controlled proximal portion 106 is signaledto assume the shape of the section that previously occupied the spacethat it is now in. The S-shaped curve propagates distally along thelength of the automatically controlled proximal portion 106 of theendoscope body 102, and the S-shaped curve appears to be fixed in space,as the endoscope body 102 withdraws proximally.

Whenever the endoscope body 102 is advanced or withdrawn, the axialmotion transducer 150 detects the change in position and the electronicmotion controller 140 propagates the selected curves proximally ordistally along the automatically controlled proximal portion 106 of theendoscope body 102 to maintain the curves in a spatially fixed position.This allows the endoscope body 102 to move through tortuous curveswithout putting unnecessary force on the wall of the colon C.

FIGS. 8-13 show the endoscope 100 of the present invention beingemployed for a colonoscopic examination of a patient's colon. In FIG. 8,the endoscope body 102 has been lubricated and inserted into thepatient's colon C through the anus A. The distal end 108 of theendoscope body 102 is advanced through the rectum R until the first turnin the colon C is reached, as observed through the ocular 124 or on avideo monitor. To negotiate the turn, the selectively steerable distalportion 104 of the endoscope body 102 is manually steered toward thesigmoid colon S by the user through the steering control 122. Thecontrol signals from the steering control 122 to the selectivelysteerable distal portion 104 are monitored by the electronic motioncontroller 140. When the correct curve of the selectively steerabledistal portion 104 for advancing the distal end 108 of the endoscopebody 102 into the sigmoid colon S has been selected, the curve is loggedinto the memory of the electronic motion controller 140 as a reference.This step can be performed in a manual mode, in which the user gives acommand to the electronic motion controller 140 to record the selectedcurve, using keyboard commands or voice commands. Alternatively, thisstep can be performed in an automatic mode, in which the user signals tothe electronic motion controller 140 that the desired curve has beenselected by advancing the endoscope body 102 distally.

Whether operated in manual mode or automatic mode, once the desiredcurve has been selected with the selectively steerable distal portion104, the endoscope body 102 is advanced distally and the selected curveis propagated proximally along the automatically controlled proximalportion 106 of the endoscope body 102 by the electronic motioncontroller 140, as described above. The curve remains fixed in spacewhile the endoscope body 102 is advanced distally through the sigmoidcolon S. In a particularly tortuous colon, the selectively steerabledistal portion 104 may have to be steered through multiple curves totraverse the sigmoid colon S.

As illustrated in FIG. 9, the user may stop the endoscope 100 at anypoint for examination or treatment of the mucosal surface or any otherfeatures within the colon C. The selectively steerable distal portion104 may be steered in any direction to examine the inside of the colonC. When the user has completed the examination of the sigmoid colon S,the selectively steerable distal portion 104 is steered in a superiordirection toward the descending colon D. Once the desired curve has beenselected with the selectively steerable distal portion 104, theendoscope body 102 is advanced distally into the descending colon D, andthe second curve as well as the first curve are propagated proximallyalong the automatically controlled proximal portion 106 of the endoscopebody 102, as shown in FIG. 10.

If, at any time, the user decides that the path taken by the endoscopebody 102 needs to be revised or corrected, the endoscope 100 may bewithdrawn proximally and the electronic motion controller 140 commandedto erase the previously selected curve. This can be done manually usingkeyboard commands or voice commands or automatically by programming theelectronic motion controller 140 to go into a revise mode when theendoscope body 102 is withdrawn a certain distance. The revised orcorrected curve is selected using the selectively steerable distalportion 104, and the endoscope body 102 is advanced as described before.

The endoscope body 102 is advanced through the descending colon D untilit reaches the left (splenic) flexure F_(l) of the colon. Here, in manycases, the endoscope body 102 must negotiate an almost 180 degreehairpin turn. As before, the desired curve is selected using theselectively steerable distal portion 104, and the endoscope body 102 isadvanced distally through the transverse colon T, as shown in FIG. 11.Each of the previously selected curves is propagated proximally alongthe automatically controlled proximal portion 106 of the endoscope body102. The same procedure is followed at the right (hepatic) flexure F_(r)of the colon and the distal end 108 of the endoscope body 102 isadvanced through the ascending colon G to the cecum E, as shown in FIG.12. The cecum E, the ileocecal valve V and the terminal portion of theileum I can be examined from this point using the selectively steerabledistal portion 104 of the endoscope body 102.

FIG. 13 shows the endoscope 100 being withdrawn through the colon C. Asthe endoscope 100 is withdrawn, the endoscope body 102 follows thepreviously selected curves by propagating the curves distally along theautomatically controlled proximal portion 106, as described above. Atany point, the user may stop the endoscope 100 for examination ortreatment of the mucosal surface or any other features within the colonC using the selectively steerable distal portion 104 of the endoscopebody 102.

In one preferred method according to the present invention, theelectronic motion controller 140 includes an electronic memory in whichis created a three-dimensional mathematical model of the patient's colonor other anatomy through which the endoscope body 102 is maneuvered. Thethree-dimensional model can be annotated by the operator to record thelocation of anatomical landmarks, lesions, polyps, biopsy samples andother features of interest. The three-dimensional model of the patient'sanatomy can be used to facilitate reinsertion of the endoscope body 102in subsequent procedures. In addition, the annotations can be used toquickly find the location of the features of interest. For example, thethree-dimensional model can be annotated with the location where abiopsy sample was taken during an exploratory endoscopy. The site of thebiopsy sample can be reliably located again in follow-up procedures totrack the progress of a potential disease process and/or to perform atherapeutic procedure at the site.

In one particularly preferred variation of this method, the electronicmotion controller 140 can be programmed, based on the three-dimensionalmodel in the electronic memory, so that the endoscope body 102 willautomatically assume the proper shape to follow the desired path as itis advanced through the patient's anatomy. In embodiments of thesteerable endoscope 100 that are configured for automatically advancingand withdrawing the endoscope body 102, as described above in connectionwith FIGS. 3, 4 and 5, the endoscope body 102 can be commanded toadvance automatically though the patient's anatomy to the site of apreviously noted lesion or other point of interest based on thethree-dimensional model in the electronic memory.

Imaging software would allow the three-dimensional model of thepatient's anatomy obtained using the steerable endoscope 100 to beviewed on a computer monitor or the like. This would facilitatecomparisons between the three-dimensional model and images obtained withother imaging modalities, for example fluoroscopy, radiography,ultrasonography, magnetic resonance imaging (MRI), computed tomography(CT scan), electron beam tomography or virtual colonoscopy. Conversely,images from these other imaging modalities can be used to map out anapproximate path or trajectory to facilitate insertion of the endoscopebody 102. In addition, images from other imaging modalities can be usedto facilitate locating suspected lesions with the steerable endoscope100. For example, images obtained using a barium-contrast radiograph ofthe colon can be used to map out an approximate path to facilitateinsertion of the endoscope body 102 into the patient's colon. Thelocation and depth of any suspected lesions seen on the radiograph canbe noted so that the endoscope body 102 can be quickly and reliablyguided to the vicinity of the lesion.

Imaging modalities that provide three-dimensional information, such asbiplanar fluoroscopy, CT or MRI, can be used to program the electronicmotion controller 140 so that the endoscope body 102 will automaticallyassume the proper shape to follow the desired path as it is advancedthrough the patient's anatomy. In embodiments of the steerable endoscope100 that are configured for automatically advancing and withdrawing theendoscope body 102, the endoscope body 102 can be commanded to advanceautomatically though the patient's anatomy along the desired path asdetermined by the three-dimensional imaging information. Similarly, theendoscope body 102 can be commanded to advance automatically to the siteof a suspected lesion or other point of interest noted on the images.

Although the endoscope of the present invention has been described foruse as a colonoscope, the endoscope can be configured for a number ofother medical and industrial applications. In addition, the presentinvention can also be configured as a catheter, cannula, surgicalinstrument or introducer sheath that uses the principles of theinvention for navigating through tortuous body channels.

In a variation of the method that is particularly applicable tolaparoscopy or thoracoscopy procedures, the steerable endoscope 100 canbe selectively maneuvered along a desired path around and between organsin a patient's body cavity. The distal end 108 of the endoscope 100 isinserted into the patient's body cavity through a natural opening,through a surgical incision or through a surgical cannula or introducer.The selectively steerable distal portion 104 can be used to explore andexamine the patient's body cavity and to select a path around andbetween the patient's organs. The electronic motion controller 140 canbe used to control the automatically controlled proximal portion 106 ofthe endoscope body 102 to follow the selected path and, if necessary, toreturn to a desired location using the three-dimensional model in theelectronic memory of the electronic motion controller 140.

While the present invention has been described herein with respect tothe exemplary embodiments and the best mode for practicing theinvention, it will be apparent to one of ordinary skill in the art thatmany modifications, improvements and subcombinations of the variousembodiments, adaptations and variations can be made to the inventionwithout departing from the spirit and scope thereof.

I claim:
 1. A method of advancing an instrument along an arbitrary path,comprising: selectively steering a distal portion of the instrument toassume a first selected curve along the arbitrary path; and advancingthe instrument distally while continuously controlling at least aproximal portion of the instrument to linearly assume the first selectedcurve of the distal portion in an infinitely variable motion bypropagating a measured length of at least one side of said distalportion to at least one side of said proximal portion.
 2. The method ofclaim 1 further comprising further advancing the instrument distallywhile controlling the proximal portion to propagate the first selectedcurve proximally along the proximal portion of the instrument.
 3. Themethod of claim 1 further comprising withdrawing the instrumentproximally while controlling the proximal portion to propagate the firstselected curve distally along the proximal portion of the instrument. 4.The method of claim 1 further comprising: selectively steering theelongate distal portion of the instrument to linearly assume a secondselected curve along the arbitrary path; and advancing the instrumentproximally while controlling the proximal portion to linearly propagatethe first and second selected curves proximally along the proximalportion of the instrument.
 5. The method of claim 1 wherein selectivelysteering the distal portion comprises manually steering the distalportion of the instrument to assume the first selected curve.
 6. Themethod of claim 1 wherein the proximal portion of the instrument isautomatically controlled by an electronic motion controller.
 7. Themethod of claim 6 further comprising measuring axial motion of theinstrument with an axial motion transducer.
 8. The method of claim 1wherein the proximal portion of the instrument is controlled such thatthe first selected curve remains approximately fixed in space as theinstrument is advanced proximally and/or withdrawn proximally.
 9. Themethod of claim 1 wherein the instrument is an endoscope inserted into apatient's body.
 10. The method of claim 1 wherein the instrument is acolonoscope inserted into a patient's colon.
 11. The method of claim 1further comprising affixing the first selected curve relative to a fixedpoint of reference while advancing the instrument distally.
 12. Themethod of claim 11 wherein the fixed point of reference is located at adistance from the arbitrary path.
 13. The method of claim 1 wherein theelongate distal portion comprises a non-segmented steerable portion. 14.The method of claim 1 wherein the proximal portion comprises a pluralityof segments pivotally interconnected between adjacent segments.
 15. Themethod of claim 1 wherein the distal portion of the instrument comprisesan elongate steerable section.
 16. The method of claim 15 wherein theelongate distal portion comprises at least one segment.
 17. A method ofadvancing an elongated instrument along an arbitrary path, the elongatedinstrument having a multiplicity of controllable sections, including afirst section, a second section and a third section, each sectionrepresenting one unit of length, comprising: continuously controllingthe first section to linearly assume a first selected curve along anarbitrary path; advancing the elongated instrument distally a distanceof approximately one unit of length while continuously controlling thesecond section to linearly assume the first selected curve in aninfinitely variable motion by propagating a first measured length of atleast one side of said first section to at least one side of said secondsection; continuously controlling the first section to linearly assume asecond selected curve along the arbitrary path; and further advancingthe elongated instrument distally a distance of approximately one unitof length while continuously controlling the second section to linearlyassume the second selected curve in an infinitely variable motion bypropagating a second measured length of at least one side of said firstsection to at least one side of said second section and continuouslycontrolling the third section to assume the first selected curve in aninfinitely variable motion by propagating the first measured length ofsaid at least one side of said first section to at least one side ofsaid third section.
 18. The method of claim 15 further comprising:controlling the first section to linearly assume a third selected curvealong the arbitrary path; and further advancing the elongated instrumentdistally a distance of approximately one unit of length whilecontrolling the second section to linearly assume the third selectedcurve and controlling the third section to assume the second selectedcurve.
 19. The method of claim 15 further comprising withdrawing theelongated instrument proximally a distance of approximately one unit oflength while controlling the first section to linearly assume the thirdselected curve, controlling the second section to linearly assume thesecond selected curve and controlling the third section to linearlyassume the first selected curve.
 20. The method of claim 15 wherein theproximal portion of the instrument is automatically controlled by anelectronic motion controller.
 21. The method of claim 15 wherein theelongated instrument is an endoscope inserted into a patient's body. 22.The method of claim 15 wherein the elongated instrument is a colonoscopeinserted into a patient's colon.